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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
441

Comunidades de anf?bios e lagartos da Ba?a de Sepetiba e do Parque Estadual do Cunhambebe, Rio de Janeiro, Brasil / Communities of amphibians and lizards of Sepetiba Bay and State Park of Cunhambebe (RJ).

Silva, Daiane Ouvernay Fernandes da 21 June 2011 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-09-15T12:14:46Z No. of bitstreams: 1 2011 - Daiane Ouvernay Fernandes da Silva.pdf: 7586481 bytes, checksum: 5a97593f1df40687d3039aaf482f7a65 (MD5) / Made available in DSpace on 2016-09-15T12:14:46Z (GMT). No. of bitstreams: 1 2011 - Daiane Ouvernay Fernandes da Silva.pdf: 7586481 bytes, checksum: 5a97593f1df40687d3039aaf482f7a65 (MD5) Previous issue date: 2011-06-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / This study investigated the relationship between species of frogs, lizards, gradients environmental and insularity. We could detect a strong relationship between lizards in open habitats and anthropic as well as a strong influence of the area to the richness and abundance of lizards, rather than habitat heterogeneity. The community was the most diverse State Park Cunhambebe. The lizards of island environments of the Sepetiba Bay showed a strong relationship between abundance and area, supporting the hypothesis of Ecological Release. The species Cycloramphus sp., Thoropa miliaris, Hylodes asper, H. phyllodes, Phasmahyla cruzi and Scinax trapicheiroi are those with lower values of tolerance of distance from this physiognomy and sometimes only occur in this environment. / Neste estudo foram investigadas as rela??es entre esp?cies de anf?bios anuros, lagartos, gradientes ambientais e insularidade. Nota-se uma forte rela??o dos lagartos com ambientes abertos e antr?picos, bem como uma forte influ?ncia da ?rea para a riqueza e abund?ncia dos lagartos, mais que a heterogeneidade de habitats. A comunidade mais diversa foi a do Parque Estadual do Cunhambebe. Os lagartos de ambientes insulares da Ba?a de Sepetiba demonstraram forte rela??o entre abund?ncia e ?rea, corroborando com a hip?tese de Libera??o ecol?gica. As esp?cies Cycloramphus sp., Thoropa miliaris, Hylodes asper, H. phyllodes, Phasmahyla cruzi e Scinax trapicheiroi s?o as que possuem menores valores de toler?ncia de dist?ncia da cachoeira e, algumas vezes, s? ocorrem neste ambiente
442

Stream-Associated Amphibian Habitat Assessment in the Portland-Vancouver Metropolitan Region

Dietrich, Andrew Evans 14 December 2012 (has links)
This study assessed the influence of landscape development on stream-associated amphibians in forested riparian areas within the Portland-Vancouver metropolitan region. Human alteration of landscapes may dramatically affect the ecology of neighboring aquatic systems. It was hypothesized that lotic amphibians would be negatively associated with greater amounts of landscape development and positively associated with forested area within the surrounding watershed. Thirty-seven 1st-3rd order streams were sampled between June 21st and September 21st in 2011. Streams potentially providing adequate habitat for stream-obligate amphibians were randomly selected. Amphibians were surveyed along 30-meter stream transects using an active-cover search (ACS). Environmental variables associated with development in surrounding landscapes were measured in situ. GIS delineation was conducted to define landscape-scale variables at stratified distances from riparian networks up-stream of each site via the utilization of the 2006 NLCD dataset and a finer-scale, regional dataset compiled by the Institute for Natural Resources (INR). Amphibians were detected at seventeen of the thirty-seven sampled streams. The most commonly detected species were Dicamptadon tenebrosus, Plethadon vehiculum and Plethadon dunni. Streams where amphibians were observed had lower average water temperature and conductivity, coarser stream substrate and were located on public property more often than streams where no amphibians were detected. Landscape variables were most significant to amphibians within 100 and 200 meters of the upstream stream network. Occupancy of a site by facultative species was best explained by the proportion of mixed forest in the surrounding watershed (R2=0.343, p<0.001). Occupancy of a stream by obligate species was best predicted by measurements of water quality and in-stream cover (Water Temperature: R2=0.275, p<0.001; Water Conductivity: R2=0.248, p<0.001; Cover: R2=0.323, p<0.001). Occupancy of stream refugia by all observed amphibians was positively influenced by higher percentages of forest cover and lower percentages of urban development and herbaceous vegetation in the surrounding watershed. Results of this study indicate that urban refugia must contain adequate riparian forest area, coarse stream substrate and clean, cool water to sustain stream-amphibian communities. Protection of remnant forested headwater stream networks is essential to the conservation of lotic amphibians in this urbanized region.
443

Variação genética e morfológica das espécies de Thoropa Cope, 1865 (Anura : Cycloramphidae) /

Sabbag, Ariadne Fares. January 2019 (has links)
Orientador: Célio Fernando Baptista Haddad / Resumo: Thoropa Cope, 1865 (Anura: Cycloramphidae) é um gênero de rãs endêmicas do domínio Mata Atlântica e de ecótonos associados. Possui atualmente seis espécies (T. miliaris, T. petropolitana, T. taophora, T. lutzi, T. megatympanum e T. saxatilis), divididas em dois grupos morfológicos: grupo petropolitana (T. petropolitana e T. lutzi) e grupo miliaris (T. miliaris, T. taophora, T. megatympanum e T. saxatilis). Todas as espécies se reproduzem e se desenvolvem em rochas molhadas de água doce, encontradas em afloramentos rochosos, cachoeiras e riachos. Um estudo recente sobre a filogenia molecular mostrou que T. miliaris é parafilética a T. taophora, e que T. taophora, T. megatympanum e T. saxatilis são monofiléticas com alto suporte (Sabbag et al. 2018). Esse estudo também encontrou diversos clados dentro de cada uma das espécies, especialmente em T. miliaris. Porém, não foi possível estudarem molecularmente as espécies do grupo petropolitana porque existe apenas uma amostra de DNA disponível para o grupo. No presente trabalho, estudamos aspectos genéticos e morfológicos das seis espécies do gênero a fim de investigar a diversidade molecular previamente encontrada, a parafilia de T. miliaris e as características morfológicas das espécies que coincidam com a diversidade genética conhecida. Encontramos que os clados conhecidos de T. miliaris são linhagens evoluindo separadamente e que os clados conhecidos de T. taophora fazem parte de uma linhagem única. Thoropa miliaris e T. taophor... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Thoropa Cope, 1865 (Anura: Cycloramphidae) is a frog genus endemic to theAtlantic forest domain and associated ecotones. It comprises six species (T. miliaris, T. petropolitana, T. taophora, T. lutzi, T. megatympanum and T. saxatilis), divided in two morphological groups: petropolitana group (T. petropolitana and T. lutzi) and miliaris group (T. miliaris, T. taophora, T. megatympanum and T. saxatilis). All the species reproduce and develop in freshwater wet rocks that can be found in rock outcrops, waterfalls and streams. A recent study on molecular phylogeny has shown that T. miliaris is paraphyletic in respect to T. taophora and that T. taophora, T. megatympanum and T. saxatilis are monophyletic with high support. This study also found many clades inside each of those species, especially within T. miliaris. Nevertheless, it was not possible to study molecular aspects of the petropolitana group because there is only one DNA sample available for the group. In this work, we studied genetic and morphological aspects of all six species of the genus in order to investigate the molecular diversity found previously, the paraphyly found for T. miliaris, and the species morphological characteristics that coincide with the known genetic diversity. We found that the known clades of T. miliaris are separately evolving lineages and that the clades of T. taophora are part of a whole lineage. Thoropa miliaris and T. taophora are reciprocally monophyletic. We also found that the diversifica... (Complete abstract click electronic access below) / Doutor
444

Participação do óxido nítrico encefálico no controle cardiovascular de rã-touro, Lithobathes catesbeianus

Zena, Lucas Aparecido 26 April 2012 (has links)
Made available in DSpace on 2016-06-02T19:22:56Z (GMT). No. of bitstreams: 1 Retido.pdf: 19733 bytes, checksum: 6aad255badc436a06364517de2344ab6 (MD5) Previous issue date: 2012-04-26 / Universidade Federal de Minas Gerais / The goal of the present study was to determine if nitric oxide (NO) acting on brain of frogs presents an inhibitory tonus on mean arterial blood pressure (MAP) and heart rate (HR) by reducing the sympathetic activity dependent on &#945; and/or &#946; adrenergic receptors during winter and spring/summer seasons. Thus, body temperature and MAP was measured by a telemetry device implanted into the abdominal cavity of American bullfrogs, with the catheter of the device inserted into the left aortic arch for AP and HR measurements. Additionally, blood cell flux was measured using a laser Doppler flowmeter sutured to the pelvic skin to calculate cutaneous vascular condutance (CVC). A guide cannula was implanted into brain lateral ventricle for injections of L-NMMA (non selective NO synthase inhibitor) or mCSF (mock cerebrospinal fluid, vehycle) and a PE cannula was inserted in the femoral vein for bolus injections of adrenergic antagonists, prazosin (&#945;1) and sotalol (&#946;), and agonists, phenylephrine (&#945;1) and isoproterenol (&#946;) or Ringer solution. Animals were maintained at 25 °C during all the experiments. Mean AP, but not HR, was greater during winter than spring/summer. L-NMMA increased MAP, but did not change HR, during both seasons. The pre-treatment with prazosin attenuated and soltalol accentuated the hypertensive effect of LNMMA in both seasons. We conclude that NO seems to act on the brain of frogs as a hypotensive agent via, at least in part, the inhibition of the symphathetic activity dependent on &#945;, and &#946;, adrenergic receptors. / O objetivo do presente trabalho foi determinar se o óxido nítrico (NO) atuando no SNC de rãs apresenta tônus inibitório sobre a pressão arterial média (PAM) e a frequência cardíaca (FC) reduzindo a atividade simpática dependente de receptores a e/ou b adrenérgicos durante o inverno e a primavera/verão. Desta forma, a temperatura corporal e a PAM foram mensuradas por meio de um transmissor de telemetria implantado na cavidade abdominal de rãs-touro, e o cateter do transmissor foi inserido no arco aórtico esquerdo para as medidas de pressão arterial e FC. Adicionalmente, o fluxo de células sanguíneas foi avaliado por meio de um sensor a laser Doppler suturado à pele da região pélvica ventral do animal para as medidas de condutância vascular cutânea (CVC). Uma cânula foi implantada no ventrículo lateral para injeções de L-NMMA (inibidor não seletivo da NOS) ou líquor artificial (veículo) e uma cânula de polietileno PE50 foi inserida na veia femoral para injeções in bolus de antagonistas adrenérgicos, prazosin (&#945;1) e sotalol (&#946;), e agonistas, fenilefrina (&#945;1) e isoproterenol (&#946;) ou solução Ringer. Os animais foram mantidos a 25 °C durante todos os experimentos. A PAM, mas não a FC, foi maior no inverno em relação à primavera/verão. A CVC da região pélvica ventral foi maior no inverno em relação à primavera/verão. O L-NMMA aumentou a PAM e diminuiu a CVC, mas não alterou a FC, durante ambas as estações. O pré-tratamento com prazosin atenuou e o sotalol acentuou o efeito pressor do L-NMMA em ambas as estações. Podemos concluir que o NO parece atuar no encéfalo de rãs como um agente hipotensor via, em parte, inibição da atividade simpática dependente de receptores alfa vasoconstritores e beta adrenérgicos vasodilatadores.
445

Ecologia tr?fica de anf?bios anuros: rela??es filogen?ticas em diferentes escalas

Amado, Talita Ferreira 17 April 2014 (has links)
Made available in DSpace on 2014-12-17T14:33:11Z (GMT). No. of bitstreams: 1 TalitaFA_DISSERT.pdf: 2140188 bytes, checksum: 0083999c43d74876b9f2f21898381161 (MD5) Previous issue date: 2014-04-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Understand the origin, maintenance and the mechanisms that operate in the current biodiversity is the major goal of ecology. Species ecology can be influenced by different factors at different scales. There are three approaches about the ecological differences between species: the first brings that differences result from current processes on niche characteristics (e.g. diet, time, space); the second that species differences are explained by random patterns of speciation, extinction and dispersion, the third that historical events explain the formation and composition of species in communities. This study aims to evaluate the influence of phylogenetic relationships in determining ecological characteristics in amphibians (globally) and test with that, if ecological differences between species of frogs are the result of ancient pre-existing differences or as result of current interactions. Another objective of this study is to verify if ecological, historical or current characteristics determine the size of species geographical distribution. The diet data for analysis of trophic ecology were collected from published literature. We performed a non-parametric MANOVA to test the existence of phylogenetic effects in diet shifts on frogs history. Thus, it is expected to know the main factors that allow the coexistence of anuran species. We performed a phylogenetic regression to analyze if niche breadth, body size and evolutionary age variables determine the size of the geographical distribution of amphibians in the Amazon. In the present study, new contributions to knowledge of major ecological patterns of anurans are discussed under a phylogenetic perspective / Entender a origem, manuten??o e os mecanismos que operam na biodiversidade atual s?o um dos principais objetivos da Ecologia. A ecologia das esp?cies pode ser influenciada por diferentes fatores em diferentes escalas. Existem tr?s abordagens a cerca das diferen?as ecol?gicas entre as esp?cies: a primeira traz essas diferen?as resultam de processos atuais atuando sobre as caracter?sticas do nicho (dieta, tempo, espa?o, etc); a segunda que diverg?ncias no nicho das esp?cies s?o explicadas por padr?es rand?micos de especia??o, dispers?o e extin??o; a terceira que eventos hist?ricos explicam a forma??o e a composi??o das esp?cies nas comunidades. Este estudo tem como objetivo avaliar a influ?ncia das rela??es filogen?ticas na determina??o de caracter?sticas ecol?gicas em anf?bios (globalmente) e testar, com isso, se as diferen?as ecol?gicas entre as esp?cies de anuros s?o resultado de diferen?as antigas pr?-existentes ou como o resultado de intera??es ecol?gicas mais recentes. Outro objetivo deste estudo ? verificar que caracter?sticas ecol?gicas, hist?ricas ou atuais, determinam e influenciam o tamanho da distribui??o geogr?fica das esp?cies. Os dados de dieta para a an?lise da ecologia tr?fica dos anf?bios foram coletados a partir da literatura j? publicada. Realizamos uma MANOVA n?o param?trica para testar a exist?ncia de efeitos filogen?ticos nas principais diverg?ncias na dieta dos anuros. Com isso, espera-se conhecer os principais fatores que permitem a coexist?ncia das esp?cies de anf?bios anuros e quais os principais n?s da filogenia de anf?bios respons?veis pelas diferen?as observadas atualmente no nicho tr?fico das esp?cies. Realizamos uma regress?o filogen?tica para analisar se as vari?veis de largura de nicho, tamanho corporal e tempo de diverg?ncia determinam o tamanho da distribui??o geogr?fica dos anf?bios anuros da Amaz?nia. Neste trabalho, novas contribui??es ao conhecimento dos padr?es ecol?gicos apresentados pelos anuros s?o fornecidas e discutidas sob uma perspectiva filogen?tica
446

Uso de recursos e padrão de co-ocorrência com insetos predadores em comunidades sub-tropicais de girinos /

Provete, Diogo Borges. January 2010 (has links)
Orientador: Itamar Alves Martins / Banca: Luis Cesar Schiesari / Banca: Lilian Casatti / Resumo: Girinos são um importante componente de ecossistemas de água doce e, ao longo dos últimos trinta anos, vêm sendo utilizados como modelos para testar hipóteses em ecologia de comunidades. O conjunto de informações disponível atualmente sugere que a presença de predadores influencia a abundância e o uso de hábitat por girinos e, conseqüentemente, a estrutura da comunidade. O objetivo deste estudo foi determinar o uso de recursos e investigar a influência de predadores na distribuição espacial de espécies e na estrutura de comunidades de girinos. As principais questões deste estudo foram: 1) qual o papel dos fatores abióticos na estruturação de comunidades de girinos?; 2) qual o grau de sobreposição de nicho entre as espécies nos três principais eixos de recursos: tempo (ocorrência sazonal), alimento e espaço (hábitat)?; 3) os girinos apresentam um padrão de distribuição não-aleatório em relação aos predadores? As amostragens tiveram freqüência mensal com coletas simultâneas de girinos e insetos predadores. Na caracterização dos corpos d'água foram utilizados dez descritores ambientais. Para determinar as guildas de espécies com relação ao uso de hábitat e ocorrência mensal foi implementada, respectivamente, uma análise de agrupamento e de ordenação por escalonamentro multidimensional não métrico. Para investigar a associação entre a abundância de girinos e os gradientes ambientais foi usada uma análise de correspondência canônica. A partilha de recursos entre girinos foi analisada utilizando-se uma análise de sobreposição de nicho em conjunto com um modelo nulo, considerando como eixos de recursos a ocorrência mensal, ocorrência nas poças e os itens alimentares. A análise da co-ocorrência pareada de girinos e predadores foi efetuada utilizando-se... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Tadpoles are an important component of freshwater ecossystems and in the last thirty years has been used as model organisms to test hypothesis in community ecology. The data currently available suggest that the presence of predators influences the abundance and habitat use by tadpoles and, consequently the community structure. The aims of this study were to establish how tadpoles divide resources and to investigate the influence of predators on species distribution and on community structure of tadpoles. The main questions were: 1) What is the role of abiotic factors in the community structure?; 2) What is the extent of niche overlap among species, considering the three main resource axes: time (seasonal occurrence), diet items and space (macrohabitat)?; 3) Tadpoles exhibit a non-random distribution pattern in relation to predaceous insects? We conducted monthly samplings to collect tadpoles and predaceous insects. We also used 10 environmental descriptors to characterize the water bodies. To recognize species guilds in relation to habitat use and monthly occurrence, we employed respectively a cluster analysis and a n-MDS, respectively. To investigate the association between species abundance and environmental gradients we used a canonical correspondence analysis. The resource partitioning among tadpoles was analyzed using a null model, considering as recource axes monthly occurrence, pond occupancy and diet items. The pair-wise co-occurrence analysis between tadpoles and predaceous insects was carried out using a null model. Our main findings demonstrate that forest canopy cover and pond hydroperiod were the main factors influencing species abundance along water bodies sampled. There was a species sorting along these two environmental gradients, with species restricted to both ends of these continuums. There was a high overlap in seasonal occurence... (Complete abstract click electronic access below) / Mestre
447

Filogeografia e genômica populacional de anuros neotropicais : estruturação, diversidade e demografia histórica /

Silva, Amanda Santiago Ferreira Lantyer. January 2019 (has links)
Orientador: Célio Fernando Baptista Haddad / Resumo: Nesta tese exploramos a diversificação de espécies de anuros da Tribo Lophyohylini distribuídas na Mata Atlântica (MA) e Caatinga, biomas do Brasil. Para tanto, utilizamos dados genômicos e métodos de filogeografia estatística para analisá-los, uma abordagem robusta e até então ainda escassa na filogeografia dos organismos sul-americanos. Através do sequenciamento Sanger amostramos trechos de DNA mitocondrial (mtDNA) e através do sequenciamento de alto rendimento obtivemos polimorfismos de nucleotídeo único (SNPs) do DNA nuclear (nDNA). No primeiro capítulo, reunimos 82 amostras da espécie Aparasphenodon brunoi que apresenta distribuição nas terras baixas e costeiras do bioma MA, sendo considerada ideal para investigar o papel da instabilidade climática do Pleistoceno em seu processo de diversificação. Ainda no primeiro capítulo, para avaliar a influência do comportamento filopátrico, associado às diferenças no modo reprodutivo, na dispersão e consequentemente, no fluxo gênico entre populações, reunimos 72 amostras de A. arapapa e A. aff. brunoi. Estas tratam-se de espécies simpátricas, de distribuição mais restrita e com modos reprodutivos contrastantes o que as tornam ideais para esse tipo de comparação. De acordo com a inferência baseada em modelos demográficos, por volta do último máximo glacial (UMG) a população norte de A. brunoi se manteve estável enquanto que a do sul experimentou um gargalo seguido de expansão recente. Além disso, a população norte de A. brunoi apres... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this dissertation we explored the diversification of anuran species of the Lophyohylini Tribe distributed in the Atlantic Forest (AF) and Caatinga biomes of Brazil. To do so, we used genomic data and methods of statistical phylogeography to analyze them, a robust and until then still scarce approach in the phylogeography of South American organisms. Through the Sanger sequencing we sampled mitochondrial DNA (mtDNA) and through high-throughput sequencing we obtained single nucleotide polymorphisms (SNPs) from nuclear DNA (nDNA). In the first chapter, we collected 82 samples of the species Aparasphenodon brunoi that is distributed in the low and coastal lands of the AF biome, being considered ideal to investigate the role of Pleistocene climatic instability in its diversification process. In the first chapter, to evaluate the influence of philopatric behavior, associated with differences in reproductive mode, dispersion and consequent gene flow among populations, we also collected 72 samples of A. arapapa and A. aff. brunoi species. These are sympatric species with a narrower distribution and with contrasting reproductive modes, making them ideal for this type of comparison. According to the inference based on demographic models, around the last glacial maximum (LGM) the northern population of A. brunoi remained stable while the southern one experienced a bottleneck followed by recent expansion. In addition, the northern population of A. brunoi exhibits greater nuclear diver... (Complete abstract click electronic access below) / Doutor
448

Analysis of Herpetofauna Diversity and Trends in Upland Northern Mississippi Hardwood Forest and Retired Farmland

Muia, Claire 03 August 2023 (has links)
No description available.
449

Non-target Impacts of Chemical Management for Invasive Plants on <i>Lithobates Pipiens</i> Tadpoles

Curtis, Amanda N. 26 November 2014 (has links)
No description available.
450

Alien invaders and reptile traders : risk assessment and modelling of trends, vectors and traits influencing introduction and establishment of alien reptiles and amphibians

Van Wilgen, Nicola Jane 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2010. / ENGLISH ABSTRACT: Biological invasions are a growing threat to biodiversity, trade and agriculture in South Africa. Though alien reptiles and amphibians (herpetofauna) are not currently a major issue, escalating problems worldwide and increased trade in South Africa suggest a possible increase in future problems. In this thesis I explore practical measures for risk assessment implementable under national legislation. I began by documenting record-keeping and legislative differences between provinces in South Africa. This revealed some serious deficiencies, complicating attempts to compile accurate inventories and discern import trends. International trade data, however, revealed an exponential increase in the number of imports to South Africa over the last 30 years. Characterising the abundance of species in this trade is important as species introduced in large numbers pose a higher establishment risk. In South Africa, I found a tendency for venomous and expensive species to be traded in low numbers, whereas species that are easy to breed and handle, or that are colourful or patterned are traded in higher numbers. Unlike South Africa, California and Florida have had a large number of well-documented herpetofaunal introductions. These introductions were used to verify the role of several key predictors in species establishment. I first evaluated the role of each variable separately. I examined different approaches for bioclimatic modelling, the predictive power of different sources of distribution data, and methods of assigning a climate-match score. I also present the first test of Darwin’s naturalization hypothesis for land vertebrates using two new phylogenies inferred for native and introduced reptiles in California and Florida. I then used boosted regression trees (BRT) to infer the relative contribution of each factor to species establishment success. Results from the BRTs were incorporated into a user-friendly spreadsheet model for use by assessors inexperienced in complex modelling techniques. Introduction effort was found to be the strongest contributor to establishment success. Furthermore, species with short juvenile periods were more likely to establish than species that started breeding later, as were species with more distant relatives in regional biotas. Average climate match and life form were also important. Of the herpetofaunal groups, frogs and lizards were most likely to establish, while snakes and turtles established at much lower rates, though analysis of all recorded herpetofaunal introductions shows slightly different patterns. Predictions made by the BRT model to independent data were relatively poor, though this is unlikely to be unique to this study and can be partially explained by missing data. Though numerous uncertainties remain in this field, many can be lessened by applying case by case rules rather than generalising across all herpetofaunal groups. The purpose for import and potential trade volume of a species will influence the threat it poses. Considering this in conjunction with a species’ environmental tolerances and previous success of species with similar life histories, should provide a reasonable and defendable estimate of establishment risk. Finally, a brief summary of the potential impacts of introduced alien herpetofauna is provided in the thesis. / AFRIKAANSE OPSOMMING: Indringer spesies hou ‘n al groter bedreiging in vir die biodiversiteit, handel en landbou van Suid- Afrika. Alhoewel uitheemse reptiele en amfibieërs (herpetofauna) tans nie ‘n groot bedreiging in Suid-Afrika is nie, dui groeiende probleme wêreldwyd asook 'n toename in plaaslike handel op moontlike toekomstige probleme. In hierdie tesis, ondersoek ek praktiese metodes vir risikobepaling wat onder nasionale wetgewing toegepas kan word. Ek begin deur die verskille in stoor van rekords en wetgewing tussen provinsies te dokumenteer. Hierdie proses het ernstige tekortkominge uitgewys, wat pogings om akkurate inventarisse saam te stel en invoertendense te bepaal, bemoeilik. Internasionale handelsdata het egter getoon dat daar ‘n eksponensiële toename in die hoeveelheid invoere na Suid-Afrika oor die laaste 30 jaar was. Die hoeveelheid spesies in hierdie handel is belangrik omdat spesies wat in groot hoeveelhede ingevoer word, ‘n hoër vestigingsrisiko het. In Suid-Afrika is ‘n tendens gevind vir handel in giftige en duur spesies teen lae hoeveelhede, terwyl spesies wat maklik teel, maklik hanteer kan word en kleurvol is of mooi patrone het, in groter hoeveelhede mee handel gedryf word. Kalifornië and Florida, in teenstelling met Suid-Afrika, het ‘n hoë aantal goed-gedokumenteerde gevalle van herpetofauna wat in die natuur vrygestel is. Hierdie introduksies was gebruik om die rol van verskeie belangrike faktore in die vestiging van populasies te bepaal. Eerstens het ek die rol van elke faktor apart ondersoek. Ek het verskillende benaderinge vir bioklimatiese model-bou ondersoek, die akuraatheid van verskillende bronne van distribusiedata getoets en drie metodes om ‘n “climate match score” te bereken, voorgestel. Ek bied ook die eerste toets van Darwin se naturalisasie-hipotese vir landwerveldiere aan, deur gebruik te maak van twee nuwe filogenieë wat ek gebou het vir inheemse en ingevoerde reptiele in Kalifornië en Florida. Ek het verder gebruik gemaak van “boosted regression trees” (BRT) om die relatiewe bydrae van elke faktor tot die vestigings-potensiaal van spesies te bepaal. Resultate van hierdie BRTs was ingekorporeerd in ‘n gebruikersvriendelike ontledingstaat wat deur bestuurders, onervare in komplekse modelboutegnieke, gebruik kan word. Invoer-hoeveelheid was die faktor wat die sterktste bygedra het tot suksesvolle vestiging. Verder is spesies met kort jeugperiodes en dié met verlangse familie in streeks-biotas, meer geskik om suksesvol te vestig. Gemiddelde klimaatooreenstemming en lewensvorm was ook belangrik. Paddas en akkedisse was die mees waarskynlikste van die herpetofauna groepe om populasies te vestig, terwyl slange en skilpaaie teen laer tempo’s populasies gevestig het, alhoewel analise van alle gedokumenteerde gevalle van herpetofauna-invoerings wêreldwyd effens verskillende tendense toon. Voorspellings wat deur die BRT-model vir onafhangklike data gemaak is was redelik swak, alhoewel hierdie resultaat onwaarskynlik nie uniek aan die studie is nie, en word gedeeltelik verduidelik deur die gebrek aan data. Alhoewel talle onsekerhede steeds bestaan, kan dié verminder word deur geval-tot-geval reëls toe te pas eerder as om vir herpetofauna as ‘n groep te veralgemeen. Die doel van invoer en potensiële handel-volumes van ‘n spesie, sal die bedreiging wat die spesie toon, bepaal. Hierdie faktore moet saam met omgewingstoleransie en voorafgaande sukses van spesies met soortgelyke lewenswyses oorweeg word, om ‘n aanvaarbare en verdedigbare beraming van vestigingsrisiko te gee. Laastens, word ‘n kort opsomming van die effekte wat uitheemse herpetofauna mag hê, verskaf.

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